How to indentify multiple USB-6501 devices?

[Sean]

We are about to use a number of USB-6501 devices in our test system.  I need a reliable way of identifying which is which.

In the past we had a system with two of these.  We just pulled a spare line High in one, Low in the other.  My Initialisation software, in LabVIEW, worked out which was which from this.  Now we are looking at using four at once, so we'd need two lines.  Perhaps we may have more in the future.  Obviously with this method we would end up using more and more DIO lines for identifying instead of doing I/O.

Unfortunately I don't have access to one of these at the moment, and we need to design the interface to it before ordering more.  If I had one I'd experiment and find out.

My first question is - can I programmatically query its serial number?  This would give me a means of identifying which is which.  However, each of our multiple test sites would then have a unique set of serial numbers, so we'd have to manage the differences between them, e.g. a file could contain each site's serial numbers.

Is there a cleverer way of doing this?  I was wondering whether I could give each device an alias name through MAX, then access them using this name?  My only concern is with the fact that it's USB - could these names vanish if a device is unplugged and plugged into a different USB port.  I don't want to rely on anything that could become broken.  If this is possible, then what is the alias name attached to?  The device's serial number or the USB location information?

Many thanks for any contributions.  I'm not being lazy, I'd experiment and find out for myself if I had one to play with!

[K_Bull]

Dear Sean,
As you must be aware you are able to name your device in MAX (alias). MAX then stores the information in its configuration file. So whenever you plug that same device in, it will route itself to the corresponding name and it is not dependent on which port it is seen.
If you have more then one device connected with distinctive names, the individual device is rightly routed to the configured device in MAX, regardless of which port they are connected to.
Also, if you are going to be using the same devices on another machine, you are able to export the configuration file to that computer. While importing you will have to link the right device as you connect them to the right one in your configuration. Once this is done, you can plug and unplug as you wish on the other computer too.
Regards,

[Sean]

Thanks for your reply, Kabul.

Can we be 110% certain that this is the case?  i.e. that DAQ alias names attach to the serial number, not the physical USB port?  Would it be possible for you to try naming two identical USB-DAQ devices, then swap their USB connections around and check that their names don't cross over to the other device?

This is really important, as I can't try this for myself and we're laying out a PCB that your OEM card will plug into.  I want to be able to tell them not to reserve any pins for ID, but I want to be absolutely certain that I can reliably identify them.

It would make sense for the alias to be attached to the serial number (in fact they'd be pretty useless without), I just want to be sure.

Thanks in advance, I promise we'll be buying these from you in sunny Newbury!  Say hello from me to Saminder if she's still there.

[K_Bull]

Hey there Sean,
Of course I checked this before I posted my previous post. I had two NI USB 6008 which I named in MAX in my PC. I then transfered the usb connections/played around with it, the right device connects to the right setting. I then exported my configuration file to another PC and then imported it there. The only thing you will have to do while importing is make sure you connect the right USB to the right one in MAX. This is the bit where you have to make a note on the device itself.
In other words, when importing a configuration file, you will have to link the devices again, so it helps to know which one is which.
Hope this helps you. If you have any more queries, please do ask!
Regards,

[Sean]

Brilliant, thanks very much for taking the time to try it.